I couldn't swear they work, but I'm willing to pay more for them for beers that are going to be aged a long time. Couldn't hurt.

Ditto here. I've used them for years. Where I buy them, they are only $1 more per bag. All I can say is that last year I opened a bottle of Wee Heavy that I made in the early 1990's, and there was no hint of oxidation in the palate (or if there was, it was certainly below my taste threshold as well as the two people I shared the brew with).

I've heard that Sierra Nevada changed their bottles from screw off caps to pry off caps just so theycould switch to O2 absorbing caps. Those guys know their sh*t.

I thought it was a new plastic that had 1/20th of the O2 getting in over time. There was a little said about it in the 2009 keynote at the NHC, and a graph. You can download it here, it is a little big.

I've heard that Sierra Nevada changed their bottles from screw off caps to pry off caps just so theycould switch to O2 absorbing caps. Those guys know their sh*t.

I thought it was a new plastic that had 1/20th of the O2 getting in over time. There was a little said about it in the 2009 keynote at the NHC, and a graph. You can download it here, it is a little big.

In my fuzzy memory, I remember someone saying they switched to pry offs (with the plastic barrier caps), then to o2 scavenging caps, and then switching back to the barrier caps because the o2 scavenging caps had no effect or a negative effect.